Add Javascript code file

Data-Structures/Array/LastElementInArray.js

@@ -0,0 +1,19 @@
+/**
+ * This function will accept an array and Return its last element 
+ * @param {Array} arr array with elements of any data type
+ * @returns {*} The last element of the array.
+ * @complexity O(1) (Best case, Average case, worst case)
+ */
+const findLastElement = (arr) => {
+    // If arr is not an array or its length is zero then the function will throw Error
+    if (!Array.isArray(arr) || arr.length === 0) {
+        throw new Error("Input must be a non-empty array.");
+    }
+    // Calculate the length of the input array
+    const array_lenght = arr.length;
+    // Calculate the index of the last element of the array
+    const LastElementIndex = array_lenght - 1;
+    return arr[LastElementIndex];
+}
+
+export { findLastElement };